Factual error: When officer Van is shot with a shotgun his body is lifted off the ground and knocked several feet backward. One of the basic laws of physics states for every action there is an equal and opposite reaction. The amount of energy required to lift and move an adult man would be tremendous and the person firing the gun would have been subjected to the same force.
Revealing mistake: When officer Van is shot with a shotgun there is one shot in which he flies backwards towards the camera in slow motion. From this point of view the launchpad (catapult), from which the officer is thrown, is visible underneath his feet.
Continuity mistake: As Kathleen gets home towards the end, she unbuttons her blouse as she walks into the bathroom to turn on the shower. She then turns around after turning on the water and her blouse is buttoned back up.